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Memory, speed of thinking get worse over time with marijuana use
Neuroscience Posted by 777 on Monday March 13, @05:59PM
from the dept.
Memory, speed of thinking and other cognitive abilities get worse over time with marijuana use, according to a new study published in the March 14, 2006, issue of "Neurology," the scientific journal of the American Academy of Neurology. The study found that frequent marijuana users performed worse than non-users on tests of cognitive abilities, including divided attention (ability to pay attention to more than one stimulus at a time) and verbal fluency (number of words generated within a time limit). Those who had used marijuana for 10 years or more had more problems with their thinking abilities than those who had used marijuana for five to 10 years. All of the marijuana users were heavy users, which was defined as smoking four or more joints per week.

"We found that the longer people used marijuana, the more deterioration they had in these cognitive abilities, especially in the ability to learn and remember new information," said study author Lambros Messinis, PhD, of the Department of Neurology of the University Hospital of Patras in Patras, Greece. "In several areas, their abilities were significant enough to be considered impaired, with more impairment in the longer-term users than the shorter-term users."

The study involved people ages 17 to 49 taking part in a drug abuse treatment program in Athens, Greece. There were 20 long-term users, 20 shorter-term users and 24 control subjects who had used marijuana at least once in their lives but not more than 20 times and not in the past two years. Those who had used any other class of drugs, such as cocaine or stimulants, during the past year or for more than three months throughout their lives were not included in the study. Before the tests were performed, all participants had to abstain from marijuana for at least 24 hours.

The marijuana users performed worse in several cognitive domains, including delayed recall, recognition and executive functions of the brain. For example, on a test measuring the ability to make decisions, long-term users had 70 percent impaired performance, compared to 55 percent impaired performance for shorter-term users and 8 percent impaired performance for non-users. In a test where participants needed to remember a list of words that had been read to them earlier, the non-users remembered an average of 12 out of 15 words, the shorter-term users remembered an average of nine words and the long-term users remembered an average of seven words.

American Academy of Neurology http://www.aan.com/press

Robin Stinnett rstinnett@aan.com

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The American Academy of Neurology, an association of more than 19,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis. For more information about the American Academy of Neurology, visit www.aan.com.

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  • The Fine Print: The following comments are owned by whoever posted them.
    ( Reply )

    Re: Memory, speed of thinking get worse over time with marijuana use
    by Patrick Casanova on Tuesday March 14, @07:17PM
    Interesting, but not suprising and not discouraging. Higher brain functioning would be even worse if the subjects had gotten drunk 4 times a week for 10 years. Fortunately, ALL of the partially impaired cognitive skills could be reacquired/improved through exercises and adequate supplementation.

    Anyway, I wonder if the subjects in this study did other drugs or drank heavily. Did the investigators control for these??
    [ Reply to this ]
    • Re: Memory, speed of thinking get worse over time
      by Allen on Thursday March 16, @05:48AM
      "Those who had used any other class of drugs, such as cocaine or stimulants, during the past year or for more than three months throughout their lives were not included in the study."

      So I would say that yes, they did control for other drugs.
      [ Reply to this ]
      • Re: Memory, speed of thinking get worse over time
        by Patrick Casanova on Friday March 17, @12:43PM
        Indeed, you're right. I contacted Stinnett and he send me the actual study along with the authors' contact info.
        [ Reply to this ]
    Re: Memory, speed of thinking get worse over time
    by sophiophile on Thursday March 16, @01:47PM
    This specific article doesn't seem to be available in the "Publish Ahead of Print" Ovid catalogue for Neurology, and unfortunately this article doesn't make clear if these were users who were still using at the time. Periods of abstinence ranging from 10-30 days in long-term users usually seem to make cognitive test scores not distinguishable (statistical significance) from controls.
    [ Reply to this ]
    • Re: Memory, speed of thinking get worse over time
      by examachine on Tuesday March 06, @06:37PM
      Are you serious? Then, this study is quite misleading.

      [ Reply to this ]

     
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